Semi-classical treatment of photon cascades in nuclei

A simple semi-classical treatment of photon cascades has been developed. The basic assumption is that a nucleus with a classical spin vector \J can be represented by the maximally aligned quantum state |J,M=J> with the quantization axis being the spin direction \J/J. It is furthermore assumed that a photon emission yields a daughter state of a similar form, |J',M'=J'>, but with its alignment direction having been modified by the emission. The overall good quality of the treatment is illustrated for a variety of E1 and E2 two-photon cascades for which non-trivial angular correlations appear. The method is suitable for use in nuclear fission simulation codes, making it possible to address photon-photon correlation observables quantitatively.